Mixing machine and method



Oct. 26 1937. c. 5.. MILLS 2,091,088

lqxme mourns AND umfion Filed A ril 25 1934 2 Sheets-Sheet 1 INVENTOR CLAUDE B. MILLS.

Ma-Z7 'AT'ToRNEY Oct. 26, 1937. Q a MILLS 4 2,097,088

mrxme mcnnm AND METHOD I Filed April 25, 1954 2 Sheets-Sheet 2 INVENTOR CLAUDE B. MH..L5,

Patented Oct. 26,1937

3 UNITED s'rA'rss MIXING MACHINE AND METHOD Claude 1:. Mills, Port Clinton, Ohio, mm... to United States Gypsum Company, Chicago, 111., a corporation of Illinois Application April 25, 1934, Serial No. 722,258

6 Claims.

Thisinvention relates to machines for mixing cementitious material. with water and relates more specifically to mixing machines and methods in which air as an optional ingredient is 5 mixed with cementltious materials and water.

In the manufacture of cementitious materials, such as gypsum wall boards and gypsum tiles and blocks, it is often desirable to make such products light in weight to improve the heat insulating m value thereof. This low density is usually obtained by introducing air into the slurry in some way so that when the slurry sets to solid form,

the resulting cast isfilled with a multitude of small air cells. I have found that by the use of a special type of mixer, compressed air can be successfully introduced into a gypsum slurry. The mixer I have devised is of a type such that it will not readily clog up and become inoperative due to the building up of set gypsum on the inside 2 of the mixer. I have found that additive fibrous materials, such as cornstalk fibers, may also be mixed with gypsum slurry and air through the use of my improved .mixer and mixing method.

An object of this invention, therefore, is to 25 provide an improved type of, mixing machine which will operate continuously over long periods of time to mix quick setting cementitlous materials, such, as calcined gypsum.

Another object of the invention is to prcvidean improved mixing machine which is suitable for introducing compressed air in a gypsum slurry so as to produce a low density cast.

A further object of the invention is to provide an improved mixing method of incorporating fibrous material and compressed air into a. gypsum slurry; also to improve mixing machines and methods in other respects hereinafter specified and claimed.

Reference is to be had to the accompanying A drawings forming a part of this specification, in

which Fig. 1 is an elevation partly in section of my 1 improved mixing machine,

Fig. 2 is a sectional elevation through the mixer 45 taken on line 2--2 of Fig. 3,

Fig. 3 is a plan view partly in section of the mixer with cover removed,

Fig. 4 is a plan view of the mixer, Fig. 5 is a bottom sectional view of the'mixer 50 (1180, I

Fig. 6 is a sectional elevation through the mixer disc taken on line 6-6 of Fig; 8, and

Fig. 7 is a sectional elevation through a modified form of mixer. v The mixing machine comprises an electric motor ill with a vertical shaft I lwhich is connected by a coupling l2 to a mixer shaft l3. Suitable bearings i4 and I! serve to rotatably support the shaft l3, said bearings being supported on frame members lid and i6 respectively. A collar l1 5 is secured near the upper end of shaft l3, said collar having an integral annular flange llon which a mixer disc i8 is supported. An annular housing 20 surrounds the disc is, said housing having a bottom 2| and a cover 22 secured to said housing by means of bolts 23 and 23a respectively. A removable lid 24 in theform of a. segment has its inner edge retained beneath a strip 2! which is secured to the cover 22. The outside edge of lid 24 is secured by hinged bolts 26 to brackets 27 on the housing 20. Handles "are secured to the lid-26 so that the lid 2E may be easily removed to permit cleaning the mixer-and making repairs.

An inlet port 29 is provided in the cover 22 between the shaft IS and the housing 20, a flange 30 being secured to said cover to connect to an inlet duct 3! which leads from a source of supply of cementitious material, such as powdered calcined gypsum. A water inlet pipe 82 is connected to the cover 22 somewhat nearer the center of shaft .2 isthan the duct 3i and arranged on one side of the duct 8! so that as the disc I! is rotated in the direction of the arrow in Fig. .4, a film of water-is deposited on the disc it to prevent the calcined gypsum from sticking to said disc. A 30 main water supply pipe 33 is secured to the cover 22 on the side of the duct at opposite the pipe 32 so as to deliver an additional supply of water necessary to produce the correct consistency in the resulting slurry. 'Ilie water inlet pipe 32 may be omitted if desired and satisfactory results will be produced. A series of compressed air inlet pipes 136, such as five in number, are preferably secured to the lid 26 around the outer edge thereof for introducing ccmpr we air, or other den- Q0 city reducing fluid into the slurry and thus pro r duce a low density cast. An air manifold not she supplies all of the air inletpipes is andan air pressure of 30-69 lbs/sq. in. is preferably maintained in this maniiold while the mixer is in operation. I

A pluraliw, such as four in number, of beater bars 96 are secured-to the upper face of disc ifipreferly equally spaced about the periphery ese beater bars 25 are preferably rectanar in cross sectionand are placed at an angle so tt the hroadiace of each beater serves to strike the mixture of calcined gypsum and water, beat the mixture into aslun'y, and

throw the slurry outwardly against the housing 20 with great force. An outlet opening 36 is provided in the housing 20 to allow the slurry to flow out of the housing 20 onto a conveyor belt 31 traveling around a pulley 38. The belt 31 serves to convey the slurry to a plasterboard machine or a block mold or to any other desired discharge point.

In order to prevent set gypsum from building up on the inside of the mixer, suitable scraping devices are provided to scrape all inside surfaces of the mixer. Scraper bars 39 of elongated form are secured at intervals around the periphery of the bottom face of disc i9 by suitable means such as riveted screws 40, said bars 39 extending at an acute angle to the disc radii so as to scrape the slurry from the upper surface of mixer bottom 2| and throw it outwardly against housing 20. A scraper bar 4| extends diametrically across the top of the mixer so as to scrape the lower surface of cover 22 and lid 24. The ends of bar 4| are preferably secured to the tops of two of the beater bars 35 by means of screws 42. The center of the bar 4! is secured by screws 43 to a driving collar 44 and said collar is secured by means of a key 45 to shaft i3. The collar 44 has a pair of diametrically opposite lugs 46 which engage in slots 41 in the disc If! so as to cause the rotation of the disc l9 and bar 4| A nut 48 secures the bar 4| and collar 44 to the upper end of shaft [3 and clamps the disc l9 onto the flange I8, said nut extending through a clearance opening 49 in the cover 22 and being covered by a cup 50. The mixer may be readily disassembled for cleaning by removing cover 212, nut 48, collar 44 and disc IS. A suitable frame member 5! supports the bottom 2| of the mixer.

In the modified and preferred form of mixer construction shown in Fig. 'l, a collar 53 is seecured to the upper end of a mixer shaft 54 by means of a nut 55 engaging a threaded section 56 on the upper end of said shaft 54, a washer 51 being interposed between said nut 55 and collar 53. An annular flange 58 is formed on the collar 53 and serves to support a mixer disc 59 which seats around an annular shoulder 5d formed on the collar 53. A stud 6| has a lower annular flange 62 seating in an internal opening 63 formed in the disc 59. A clearance space 66 is formed in the bottom of stud 6| to clear the nut 55. An outstanding annular flange 65 is formed on the stud BI and bolts 63 serve to firmly secure the disc 59 between flanges 58 and 55. A diametrically arranged slot 81 formed in the top of stud 6| serves to receive a scraper bar 68 similar to bar 4!, a bolt 69 securing said bar 68 to said stud. A central opening 10 is formed in a cover 'Il above the stud 6|, and is closed by an annular plate 12. The other details of the modified form of mixer are substantially the same as in the device shown in Figs. 1 to 6.

My improved mixer will mix calcined gypsum slurry continuously for long periods of time without a shut down. I prefer to mix vegetable fibers, such as cornstalk fibers with the calcined gypsum entering the inlet port 29 and the mixer makes a very smooth slurry of highly desirable characteristics even with the use of fibers in the mix. The introduction of compressed air through pipes 34 can be readily, controlled by suitable valves to give any desired density in the resulting cast.

I would state in conclusion that while the illustrated example constitutes a practical emiodiment of my invention, I do not wish to limit myself precisely to these details, since manifestly, the same may be considerably varied withou departing from the spirit of the invention as defined in the appended claims.

Having thus described my invention, I claim as new and desire to secure by Letters Patent:-

1. The method of producing a slurry of calcined gypsum containing entrained air, comprising means for introducing compressed air into said housing adjacent the periphery of said disc, and beaters positioned adjacent the periphery of said disc for mixing the ingredients to deliver a slurry containing entrained air from said port.

3. In a mixing machine for gy'psum slurries, :1:

a disc rotatably mounted about a substantially vertical axis, a housing enclosing said disc and having an outlet port, beaters extending vertically adjacent the periphery of said disc, scrapers for cleaning the inside surfaces of said housing, and

means for introducing materials to be mixed into said housing on top of said disc.

4. The method of mixing materials, which comprises depositing a film of water onto the upper surface of a disc rotating at a high speed, depositing a quick setting cementitious material onto said water film, adding additional water to said cementitious material, introducing 'air into said mixture, and beating the mixture to form a slurry containing entrained air.

5. In a mixing machine for gypsum slurries, a disc rotatably mounted about a substantially vertical axis, a housing enclosing said disc and having a cover and an outlet port, means for introducing calcined gypsum and water into said housing onto said disc, beaters on said disc to mix said water and calcined gypsum into a slurry to be delivered from said outlet port, and a scraper rotating with said disc and connected to some of said beaters for scraping the inside of said hous- I surface of said housing bottom.

CLAUDE B. MILLS. 

